Despite his will, Jim Harbaugh was stuck.

By most appearances, Alex Smith had become elite, just as Harbaugh had said he would. He was #1 in completion percentage, #2 in yards per throw, #3 in quarterback rating. And not entirely coincidentally, the Niners had continued to win.

And yet, by a single crucial measure, Alex Smith had simply failed.

A deep, explosive passing-game. These days, it's the key to success. Sure, we'd almost reached the Super Bowl without one. But "almost" doesn't cut it. To take the next step, we had to improve. To take the next step, we had to have it.

Smith was given all the tools. A full preseason as the unquestioned starter. A second year in Harbaugh's scheme. A fleet of new and dangerous toys. And yet it simply wasn't there.

You like statistics? I'll give you some. In 2011, Smith went deep—more than 15 yards downfield—with 17% of his throws. This year, that percentage has dropped—to 13.8. Despite a near-total organizational commitment to increasing our offensive aggressiveness, there's no QB less aggressive than Smith.

Having no choice but to look elsewhere for explosive potential, Harbaugh had given token appearances to Colin Kaepernick, athletically freakish but wholly unproven. Yet this was too disruptive for Smith, so Harbaugh had retreated, into a dilemma he couldn't escape.

Smith was playing too well to be benched. And, of course, the Niners were winning. But Smith wasn't providing the missing piece. Kaepernick might provide that piece, but perhaps at the cost of efficiency, and thus perhaps at the cost of winning.

To any coach, this would be tough. To a coach as crazily high-strung as Harbaugh, it was almost heartstopping.

Yet he was about to be let off the hook.

After Smith sustained his concussion, Kaepernick's relief appearance didn't exactly quiet the issue. True, he didn't seem ready to start; but he showed enough, especially late, to keep the dilemma alive. If he played okay after coming in cold, how would he do if he knew he would start?

As the week progressed, it seemed that Smith was on track to return, infusing in me that typical mix, equal parts relief and dread. There's comfort, of course, in the devil you know. And once again, the guy seems to win. But his timid efficiency is more than just soul-drainingly dull. It's also likely a playoff loser, and thus, in the end, a season's waste.

Likewise, the late announcement that Smith wasn't cleared—that Kaepernick would get his first start—produced its own emotional mix. Clearly there was a dash of fear. An important game, on Monday night, against the league's most opportunistic D? Quite arguably, no first-starter had ever drawn a tougher assignment. Yet the guy is just so damn exciting, he reminds you why you love this game.

Most importantly, though, he would answer the question. Never mind the tough conditions. If he went out and laid an egg, Harbaugh would know to stick with Smith. For better or worse, Smith would be his only option. But if Kaepernick played efficiently, while adding that explosiveness—especially under those tough conditions—well, Harbaugh would know what to do then too.

Kaepernick was astonishing. With the Bears expecting timidity—how often is a team more aggressive with its backup QB?—Kaepernick came out firing. He stood tall in the pocket, he went through his progressions, he extended plays without giving up. He threw strikes with zip and touch. And best of all, he threw deep, even into the tightest windows. (In fact, Kaepernick has gone deep with 26.5% of his throws; if he qualified, that would rank him third.) His arm was so deadly that he didn't even need to use his equally-deadly running skills. And he didn't make a single mistake, finishing with a rating north of 130.

As it often does, the offensive energy spread to our D, which simply overwhelmed the Bears. Aldon Smith went nuts—mostly from the D-line, I'd point out—and the Bears' morale dissolved immediately.

By the time Kaepernick threw for his second score, early in the second half, it was 27-zip. And Harbaugh had his solution at last.

Asked the obvious question, Harbaugh said he'd go with the "hot hand." This, of course, is not what you say when you've got unshakable faith in your starter. (Immediately regretting his unusual candor, he lamely asserted that both QBs have got "hot hands," but the cat was already out of that bag.) Sure, we know that backups often make strong first-impressions that they're unable to sustain. But though he might not play like this every week—future opponents will see him coming—this isn't some low-rent flash in the pan, the second coming of Troy Smith. This, again, is Harbaugh's choice, doing what he was drafted to do: giving life to Harbaugh's nearly violent aggression. It was only a matter of when he'd be ready. And Monday proved he's ready now.

And now that he's ready, there isn't a viable case for Smith. Your only argument is that he's a "winner," with those staggering efficiency stats. But don't you see? Any competent pro QB should complete 70% of his passes, for eight yards per, when all he throws are eight-yard passes. That doesn't make him a "winner"; it makes him a guy who happens to win—at least until playoff time, of course, when we'd once again be playing one-handed, with the same, sad, sorry result.

Kaepernick reminded us of what real quarterbacking is. It's efficient, sure, but it's so much more. It maximizes every snap. It senses opportunity, and then exploits it. It vitalizes one team and intimidates the other. It's absolutely thrilling, especially after a decade away.

And it can truly win it all.